Stuffing boxes are commonly used in the oilfield to create a seal between the wellhead and the well tubulars, such as rod string, passing through the wellhead to drive the downhole pump. Conventional stuffing boxes typically comprise a stationary box portion adapted to receive and create a seal with the moving tubular passing through the box in order to retain fluid pressures and prevent the leakage of wellbore fluids.
Often, the stuffing box is secured around the uppermost rod, referred to as the “polished rod”. In order to allow for the polished rod to move through the box without damage, one or more packing rings are positioned within the box and concentrically disposed around the shaft of the rod. Such designs are operational when the rod is properly aligned with the box however, over time, abrasive materials in the wellbore fluid or uneven forces imposed upon the rings due to misalignment of the polished rod can cause the inner periphery of the packing rings to wear down causing leakages. The need to realign the polished rod and to replace worn down packing rings costs oil companies in service time, down-time, and environmental cleanup.
Replacement of packing rings is difficult in known stuffing boxes due to inaccessibility of the rings, and the rings becoming hard or brittle over time, making their removal difficult, dangerous, and time consuming. There is a need for a modified, adjustable stuffing box providing for easy access to packing rings.
Stuffing boxes typically provide a safety valve for closing the wellbore in the catastrophic event of breakage of the polished rod. Known valves typically comprise a movable portion that is hingedly attached to the stuffing box in a manner to allow the uni-directional movable portion to pivot from an “open” position (allowing the flow of wellbore fluids) to a “closed” positions, the closed position effectively sealing the surface off from wellbore fluids.
Given its position within the wellbore, conventional valves are commonly exposed to wellbore fluids that wear on the valve components over time, ultimately damaging the valve and allowing fluids to escape through the seal.
There is a need for a modified stuffing box adapted to prevent the safety seal from being exposed to wellbore fluids. There is a need for the modified stuffing box to provide a simple safety valve, minimizing the number of mechanical components required to seal the wellhead.